Simple hack reuses an air freshener PIR sensor

A year ago [Lochie] bought an Airwick automatic air freshener, and while he thought it was a cool gadget, the freshening spray and the novelty ran out in short order. The device collected dust in his room for some a while until he recently unearthed it, and noticed that a perfectly good PIR sensor was looking him in the face all this time.

He disassembled the air freshener, then set out to figure out how he could interface with the PIR sensor. After finding a helpful Instructable on the topic, he had full access to the sensor’s signals, allowing him to easily wire it up to an Arduino. He decided it would be fun to trigger some simple music any time someone entered his room, so he encoded a short bit of the Super Mario Brothers theme in RTTTL, as he explains in the video below.

It’s a simple little hack, but [Lochie] is pleased with it, and we imagine that he likely has a long list of other creative ideas in mind for his newly discovered PIR sensor.

5 thoughts on “Simple hack reuses an air freshener PIR sensor”

I had an idea for two or three of these sensors:
Arrange them in an array and use the order and relative time of their activation to detect the direction and speed of a passing hand, person, etc. (depending on how/where you mount the array). Think of the door switches on “Moya” in the Farscape TV show, for example. If you had two, you could make a 1-dimensional sensor (like the aforesaid switches seem to be) or use three for two dimensions. You could use it as a simple gesture system to control, say, an audio player, among many other uses.

I thought immediately of a motion-sensed light for the space under the shelf that holds up my monitor. I like to work in low light and it gets dark under the shelf and it would be cool to have a light that turns on when my hand approaches to reach for something. This might be something I actually try!